Rinse aid compositions

ABSTRACT

THE INVENTION DISCLOSED IS DIRECTED TO A RINSE FOR USE IN MECHANICAL DISHWASHING MACHINES AND INCLUDES PRESCRIBED AMOUNTS OF AN ALKALI METAL OR AMMONIUM SALT OF AN ALCOHOL SULFATE OF THE FORMULA ROSO3H WHERE R IS AN ALKYL GROUP HAVING ABOUT 5 TO 9 CARBON ATOMS, AND PRESCRIBED AMOUNTS OF A DEFINED MONIOMIC SURFACTANT. THE RINSE AID MAY FURTHER INCLUDE MATERIALS SUCH AS DEFOAMING AGENTS, SOLVENTS, INGREDIENTS TO PRECIPITATE HARD WATER SALTS, AND THE LIKE.

United States Patent 3,563,901 RINSE AID COMPOSITIONS Homer E. Crotty,Cincinnati, Ohio, assignor to W. R.

Grace & C0.,- New York, N.Y., a corporation of Connecticut No Drawing.Continuation of application Ser. No.

571,989, Aug. 12, 1966. This application Feb. 26,

1970, Ser. No. 18,016

Int. Cl. C1111 3/04 US. Cl. 252136 8 Claims ABSTRACT OF THE DISCLOSUREThe invention disclosed is directed to a rinse aid for use in mechanicaldishwashing machines and includes prescribed amounts of an alkali metalor ammonium salt of an alcohol sulfate of the formula ROSO H where R isan alkyl group having about to 9 carbon atoms, and prescribed amounts ofa defined nonionic surfactant. The rinse aid may further includematerials such as defoaming agents, solvents, ingredients to precipitatehard water salts, and the like.

This application is a continuation of application Ser. No. 571,989,filed Aug. 12, 1966, now abandoned.

This invention relates to compositions suitable for use as a rinse aidin mechanical dishwashing machines.

Practically all larger restaurants and commercial and institutional foodhandling installations are equipped with one or more mechanicaldishwashing machines. There is, furthermore, an increasing market forthe home dishwashing machine. In the larger institutional type ofmachine the dishes and utensils are placed on racks or a belt andconveyed through various cycles and/or chambers of the dishwashingmachine. The stages or cycles usually include a pre-rinse of warm waterat about 110 to 120 F., a spray wash at about 140 to 160 F. usingapproximately a 0.2 percent aqueous solution of detergent, a warm waterrinse at about 170 to 190 F. and a final rinse at about 180 to 200 F.Normally, the pre-rinse, wash and water rinse chambers of the machinecontain a tank to hold the liquid, a pump and spray nozzles arrangedparallel to the belt so that the dishes are sprayed from the top andbottom as they are conveyed through the machine so that all areas of thedishes and utensils are reached by the liquid sprays. The final rinse isa high pressure mist-type spray which is normally perpendicular to thedirection of travel of the dishes. The final rinse time is typicallyabout 5 to 10 seconds. The final rinse temperature is usually about 180to 200 F. as a sanitation measure and to speed drying time.

As is known in the art, the final rinse water contains a very smallamount (approximately 200 parts per million) of a surface active rinseaid composition to promote wetting and to produce a sheet fiow, therebyreducing water spotting, increasing the run off speed of the water andreducing the drying time.

In all mechanical dishwashing equipment, a serious problem results fromaeration and foaming of the washing solution or rinsing water. The foamis produced primarily by the accumulation of protein food soils .(suchas egg solids and milk solids) during the various cycles as the dishesare washed. These materials have a natural tendency to foam. Also, sincemost dishwashing detergents are composed of inorganic alkaline salts(e.g., carbonates, silicates, phosphates and hydroxides), the fatty foodsoils become saponified in the hot solution and produce copious foam inthe machine, even though the inorganic dishwashing detergents do notfoam in 3,563,901 Patented Feb. 16, 1971 themselves. The foam not onlycauses the machines to overflow but also, and more importantly, reducesthe pressure of the sprays and cleaning efficiency. Such foaming hasbeen known to burn out pump motors because of overload.

It is known in the art that addition of a small amount (usually 0.5 to 4weight percent of nonionic, high molecular weight polyoxyalkylene)glycols or high molecular weight alcohols to the inorganic detergentformulation will decrease the foaming effect of food soils. However, theuse of a rinse aid in the final rinse spray produces a major undesirablecounteraction. Due to splash and/or physical construction of themachine, a portion of the final rinse spray carries back into the rinsesection, the wash section or the pre-rinse section of the machine. Thelow-foaming or non-foaming surfactants best suited for use in the finalrinse spray at 180 to 200 F. frequently contribute to foaming in theother sections or cycles of the dishwashing machine, which operate atlower temperatures. Moreover, all commercial surfactants used fordefoaming food soil, produce relatively very poor sheet flow in thefinal rinse, and leave streaks and residue on glassware and dishware.They frequently congeal when injected into the 180 to 200 F. final rinsewater and form spots and streaks on glassware.

They have been known to congeal and clog the small diameter injectionlines and nozzles in the final rinse spray system.

It is an object of this invention to provide an improved rinse aidcomposition which is not subject to the above limitations.

Another object of this invention is to provide a final rinse aidcomposition which gives good sheet flow and little or no residue (andconsequent spotting) and which also, at the same time, does notcontribute to foaming in the preceding sections or cycles of mechanicaldishwashing machines.

Still another object of this invention is to provide a method fordecreasing the foam production in mechanical dishwashers resulting fromthe rinse aid compositions used in the final rinse section or cyclewhile retaining desired good sheet fiow and low residue.

Further objects and the many advantages of this invention will becomeapparent to those skilled in the art after considering the followingmore detailed disclosure.

It has been discovered that the objectives of this invention can beachieved by a rinse aid composition containing a unique blend of surfaceactive agents including, as essential ingredients, an alkali metal orammonium salt (e.g., the sodium salt) of an alcohol sulfate having theformula ROSO H, wherein R is an alkyl group having about 5 to 9 carbonatoms (which group may be either straight or branched chain) and anonionic surfactant which is a poly (oxyalkylene) condensate with anactive hydrogen-containing organic precursor.

Examples of suitable alcohol sulfate salts are sodium n-octyl sulfate,sodium n-hexyl sulfate, sodium Z-ethyll-hexyl sulfate, and sodium2-ethyl-4-methyl-l-phenyl sulfate. The said alcohol sulfate saltsprovide excellent sheet flow, reduced water spotting, little or noresidue, high cloud point, and fast wetting properties in the finalrinse. They do tend to contribute to foaming in the other cycles orsections of the mechanical dishwashing machine and, because of theirexcellent wetting, tend to hinder the desired fast drying. To overcomethese undesirable effects the alcohol sulfate salts used in the rinseaid compositions of this invention are blended with the commerciallyavailable low foaming nonionic poly (oxyalkylene) condensates withactive hydrogen-containing organic compounds which have previously beenused, per se, as the surface active agent in final rinse aidcompositions.

Typical examples of suitable nonionic wetting agents used as the secondessential ingredient in the rinse aid compositions of this invention arethe following commercially available materials which are identified bythe respective manufacturers as indicated:

(a) Igepal CO-210, -430, 520, 610, -630, -633, 710,

730 and -850 [nonylphenoxypoly(ethyleneoxy)ethanol];

(b) Pluronic -L 42, L 43, L 44, L 61, L, 62, L 63, L 64, L 72, L 92 andL 101 (condensate of ethylene oxide with a hydrophobic base formed bycondensing propylene oxide with propylene glycol);

(c) Plurafac RA-10 (polyoxyalkylene block copolymer);

((1) Surfonic LF-6 and LF-7 (alkyl polyoxyalkylene ethers);

(e) Triton CF10, and CF-Zl (alkylaryl polyether);

(f) Triton N-100, -10l, and N-128 (nonyl phenyl polyethoxy ethanol) (g)Tergitol NP-33, 35, -40 and NP-44 (nonyl phenyl polyethylene glycolether);

(h) Igepal LO-210, 430, -530, 610, -630, 710, 720

and LO-730 [straight chain nonplphenoxypoly(ethy1- eneoxy)ethanols] (i)Antarox BL330 and BL340 (alifatic (sic) polyether);

(j) Plurafac A 16, A 25, A 26, B 16, and B 26 ,(oxyethylated straightchain alcohols);

(k) Biosoft EA-lO and EA-12 (ethoxylated fatty alcohol);

(l) Makon NF-S and NF-12 (polyalkoxylated aliphatic base);

(m) Tergitol 15-5-3 and 15-8-9 (polyethylene glycol ether of linearsecondary alcohol);

(n) Surfonic LF-16 and LF-17 ,(alkyl polyoxyalkylene ethers);

(o) Sterox MJ-b (alkyl phenol ethylene oxide adduct);

and

(p) Surfactant DF 12 and DF 14 (polyethoxylated straight chain alcohol).

It is highly desirable that the surface active agents be biodegradableand for this reason, the rinse aid compositions most preferably containas the essential ingredients a biodegradable alcohol sulfate salt suchas sodium n-hexyl or sodium n-octyl sulfate and a biodegradable nonionicsurfactant such as those included in items (h) through (p) in theforegoing listing of suitable nonionic surfactants.

The final rinse aid compositions of this invention include from about toabout 40 parts, by weight, of the alcohol sulfate salt and from about 5to about 40 parts, by weight of the nonionic poly (oxyalkylene)condensate surfactant. The weight ratio of sulfate salt to the nonionicsurfactant may range from about 0.5 to about 5.0 but preferably rangesfrom about 0.75 to about 1.5.

The improved final rinse aid compositions may be, but are notnecessarily, prepared in the form of solutions suitable for use, as is,by the ultimate user. The most suitable solvent is water where this isappropriate. Occasionally, depending upon the particular materialschosen for formulation into the improved rinse aid compositions, a minorproportion of a co-solvent such as ethanol, isopropanol or butylCellosolve (defined in The Merck Index 7th Ed. at page 180 to beethylene glycol monobutyl ether) is used to assure complete dissolutionof the rinse aid ingredients. Typically this will involve, when desired,the use of a solvent comprising water and up to about 25 percent byweight (based on total weight) of a co-solvent, e.g., isopropanol.Specific ranges for any particular case will, of course, depend upon thespecific ingredients to be dissolved and their relative proportions.Routine empirical testing and/or the specific examples presentedhereinafter will suffice to show those skilled in the art the generaland preferred ranges of co-solvent proportions. In all cases thesolvents chosen should provide stable solutions at temperatures rangingfrom ambient temperature up to at least about F. This temperaturestability is important for purposes of shipment under various weatherconditions and also to preclude clouding or precipitation from solutionin the reservoir of the dispensing equipment for the rinse aidcomposition, which is usually mounted on or closely adjacent to themechanical dishwasher.

In addition to the essential ingredients described above, the finalrinse aid compositions of this invention may include, as optionaladditional ingredients any one, or a combination of, a defoaming agent,an acidifying material which serves to inhibit precipitation of waterhardness salts, and an anionic wetting agent to increase wetting anddecrease residue.

Suitable defoaming agents for the compositions of this invention includehigh molecular weight (from about 3,000 to 5,000)poly(oxyalkylene)glycols and higher aliphatic monohydric alcohols suchas those containing from about 8 to about 10 carbon atoms. The defoamingagents, when used, typically comprise from a small amount up to about 10percent of the total weight of the rinse aid compositions.

The acidifying agents which may be used to inhibit precipitation of hardwater salts may be either inorganic or organic acids. Suitable inorganicacids are hydrochloric and phosphoric acids. Examples of organic acidswhich may be used are glycolic, tartaric, citric, lactic and glyconicacids. These ingredients, when used, typically comprise from a smallamount up to about 10 percent of the total weight of the rinse aidcompositions.

A wide variety of other anionic wetting agents may be used in thepractice of this invention. In general, it has been observed thatalthough they exhibit excellent wetting and frequently show very littleresidue, they also have the undesirable features of foaming in the finaldishwasher rinse as well as contributing to production of copious foamin the wash and rinse compartments or cycles of the dishwasher. Inaddition they also lead to slow run off and drying time. Preferablythese additional optional ingredients will not be used in thecompositions of this invention. If their presence is found desirable forsome special purpose, the concentration is kept as low as possible,typically on the order of from a small amount up to not more than 5percent of the total weight. Suitable additional anionic surfactantswhich may be used include sodium lauroyl sarcosinate; sodium dihexylsulfosuccinate; sodium di-octyl sulfosuccinate; dodecyl and tridecylbenzene sulfonic acid; sodium aliphatic phosphate esters, and alkylnaphthylene sodium sulfonate.

The invention is further shown by the following specific non-limitingexamples.

EXAMPLES The following are representative specific examples of finalrinse aid compositions within the scope of the present invention. Eachhas been found, in laboratory and preliminary field testing, to beeminently suitable for the intended purposes. Each was found to produceeither slight or no foam in the wash section and the water rinsesections or cycles of mechanical dishwashing machines in which they weretested. All exhibited fast drying time on glassware, on china andplastic dishes and on silverware with a minimum of residue andstreaking.

EXAMPLE 1 Weight percent Water 40.0 Sodium 2-ethylhexyl sulfate 25.0Polyalkoxylated aliphatic base (Makon NF-S) 20.0 70% phosphoric acid10.0

Anionic surfactant (aliphatic phosphate ester) 5.0

5 EXAMPLE 2 Weight percent Water 47.0 Polyalkoxylated aliphatic base(Makon NF-5) 8.0 Sodium Z-ethyl hexyl sulfate 35.0 50% aqueous lacticacid 10.0

EXAMPLE 3 Water 52.0 Sodium n-octyl sulfate 20.0 Poly(oxyethy1ene)glycol5.0 50% aqueous lactic acid 10.0 Aliphatic polyether (Antarox BL330)13.0

Molecular weight between 3,000 and 5,000.

EXAMPLE 4 Water 44.5 Isopropanol 5.5 Sodium 2-ethy1 hexyl sulfate 30.0Polyet-hoxylated alcohol (surfactant DF-l2) 20.0

EXAMPLE 5 Water 50.0 Polyalkoxylated aliphatic base (Makon NF-12) 20.0Sodium 2-ethyl hexyl sulfate 30.0

EXAMPLE 6 Water 45.4 Isopropanol 9.0 Sodium n-octyl sulfate 25.0 Sodiumlauroyl sarcosinate 1.8 Sodium di-hexyl sulfosuccinate 3.5Poly(oxyalkylene)glycol 1.8 Aliphatic polyether (Antarox BL-340) 13.8

Molecular weight between 3,000 and 5,000.

EXAMPLE 7 Water 49.64 Aliphatic polyether (Antarox BL-330) 13.50 Sodiumlauroyl sarcosinate 2.00 Sodium di-hexyl sulfosuccinate 1.00 Sodiumn-hexyl sulfate 20.00 Polyoxy(alkylene)glycol 4.86 Isopropanol 9.00

Molecular weight between 3,000 and 5,000.

EXAMPLE 8 Water 63.50 Aliphatic polyether (Antarox Bil-330) 15.00 Sodiumn-octyl sulfate 15.00 Polyoxy(alkylene)glycol 6.00 Di-octyl ester ofsulfosuccinic 0.50

Molecular Weight between 3,000 and 5,000.

EXAMPLE 9 Water 51.0 Isopropanol 10.0 Alkyl polyoxyalkylene ether(Surfonic LF-l6 or LF-17) 15.4 Sodium n-octyl sulfate 17.7Polyoxy(alkylenc)glycol 5.9

Molecular weight between 3,000 and 5,000.

EXAMPLE 10 Water 57.0 Isopropanol 10.0 Aliphatic polyether (AntaroxBL-330) 13.0 Sodium n-oxtyl sulfate 15.0 Polyoxy(alkylene)glycol 5.0

Molecular weight between 3,000 and 5,000.

The following are specific examples of final rinse aid compositionsfound in laboratory testing to be unsuitable for the intended purposes.

6 EXAMPLE 11 Weight percent Water 75.0 Igepal L 630 25.0

This composition caused high foaming in the machine.

EXAMPLE 12 Weight percent Water 41.0 Sterox MJ6 22.0 Makon NF-S 37.0

Poor sheet flow, residue on glassware, and excessive foaming in themachine were observed.

15 EXAMPLE 13 Weight percent Water 35.0 Sodium Xylene sulfonate 15.0Makon NF-S 50.0

Poor sheet flow, residue on glassware, and excessive foaming in themachine were observed.

EXAMPLE 14 Weight percent Water 55.0 Tergitol 15S9 7.5 Tergitol 15S313.5 Makon NF-S 24.0

Blotchy sheet flow and residue on glassware was observed.

EXAMPLE 15 Weight percent Water 50.0 Triton CF 32 25.0 Peronic L61 25.0

1 Amine polyglycol condensate.

Blotchy sheet flow and residue on glassware was observed.

EXAMPLE 16 Weight percent Water 75.0 Antarox BL 330 25.0

Blotchy sheet flow and residue on glassware was observed.

EXAMPLE 17 Weight percent Water 50.0 Triton CF-14 45.0

Biosoft EA 10 Residue on glassware was observed.

Ethylene oxide adduct of straight chain alcohols,

High foam in the machine and residue on glassware was observed.

'EXAMPLE 19 Weight percent Water 55.0 Tergitol15-S3 22.5

Tergitol 15-S9 22.5

Poor shee't flow and residue on glassware was observed.

Poor sheet flow, residue on glassware and excessive foaming in themachine was observed.

EXAMPLE 21 Weight percent Water 75.0 Sterox MJ-B 25.0

Foaming in the machine was observed.

EXAMPLE 22 Weight percent Water and isopropanol 75.0 Hyonie PE-O 25.0

1 Alkyl phenoxy polyoxyethylene ethanol.

Poor sheet flow and foaming in the machine was observed.

Obviously, many modifications and variations of the invention ashereinabove set forth can be made without departing from the essence andscope thereof, and only such limitations should be applied as areindicated in the claims.

What is claimed is:

1. A composition suitable for use as a rinse aid in a mechanicaldishwasher which consists essentially of (A) from about 5 to about 40parts by weight of an alkali metal or ammonium salt of an alcoholsulfate having the formula ROSO H wherein R is an alkyl group havingabout 5 to 9 carbon atoms, and

(B) from about 5 to 40 parts by weight of a nonionic surfactant which isa poly(oxyalkylene) condensate with an active hydrogen containingorganic precursor,

(C) the weight ratio of (A) to (B) ranging from about 0.5 to about 5.0.

2. The composition of claim 1 wherein the ratio of (A) to (B) is about0.75 to about 1.5.

3. The composition of claim 1 which includes a solvent member of thegroup consisting of water and mixtures of water with a co-solventselected from the group consisting of ethanol, isopropanol and ethyleneglycol monobutyl ether; said water solvent being present in an amountfrom 40 percent to 63.5 percent by weight and said cosolvent beingpresent in an amount from 5.5 percent up to about 25 percent by weight,all percentages based on the total weight of the composition.

4. The composition of claim 1 wherein said alcohol sulfate is selectedfrom the group consisting of sodium n-octyl sulfate, sodium n-hexylsulfate, sodium 2-ethyl-lhexylsulfate, and sodium2-ethyl-4-methyl-l-pentyl sulfate.

5. The composition of claim 1 which includes from a small amount up toabout 10 percent by weight of the total weight of the composition, ofpolyoxyalkylene glycol having a molecular weight of from about 2,000 toabout 5,000 or aliphatic monohydric alcohol containing from about 8 toabout 10 carbon atoms, as a defoaming agent.

6. The composition of claim 1 which includes from a small amount up toabout 10 percent by weight of the total weight of the composition, of anacid selected from the group consisting of hydrochloric, phosphoric,glycolic, tartaric, citric, gluconic, and lactic acid and mixturesthereof to inhibit precipitation of hard water salts.

7. The composition of claim 1 which includes from 0.5 to 5 percent byweight of the total weight of the composition, of an anionic surfactantselected from the group consisting of sodium lauroyl sarcosinate, sodiumdihexyl sulfosuccinate, sodium dioctyl sulfosuccinate, dodecylandtridecyl-benzene sulfonic acid.

8. The composition of claim 5 wherein said alcohol sulfate is sodiumn-octyl sulfate in an amount of about 15 parts by weight, said nonionicsurfactant is biodegradable and appears in an amount of about 13 partsby weight, said solvent is present in an amount of about 67 parts byweight formed of about 57 parts by weight water and about 10 parts byweight of isopropanol, and said deforming agent is present in an amountof about 5 parts by weight.

References Cited UNITED STATES PATENTS 1/1960 Hearn et al 25289 3/1963Temble et al 25289 OTHER REFERENCES HERBERT B. GUYNN, Primary ExaminerW. E. SCHULZ, Assistant Examiner U.S. Cl. X.R.

